Interpretive Summary: Development of low-phytate crops is desirable since it will improve the nutritional value of grains when used in monogastric animal feeds and also possibly when used in human foods. Development of crop with either “high” or “low” seed total phosphorus, different characteristics than “low-phytate”, would also be useful, particularly for ruminant feeds such as dairy production and for biofuels production. One tool that will be very helpful in breeding these types of crops would be to identify useful genes and alleles. New methods and the science underlying them are described. This work will advance our ability to breed or engineer seed crops better suited to use in feeds, foods and biofuels production. It will also provide useful resources for advancing our understanding of plant and seed biology.

Technical Abstract:
Both the chemical composition and total amount of seed phosphorus (P) are important to the end-use quality of cereal and legume seed crops. The chemistry of seed total P largely revolves around the synthesis and storage of phytic acid (myo-inositol hexaphosphate). Forward genetics research, beginning with the isolation of low phytic acid (lpa) mutants, has led to the identification of genes encoding functions important to phytic acid synthesis and transport in seeds. Lpa mutations have been isolated in maize (Zea mays L.), barley (Hordeum vulgare L.), rice (Oryza sativa L.), wheat (Triticum aestivum L.) and soybean (Glycine max L. (Merr.)), and chromosomal mapping has identified as many as six non-linked loci in a single species (barley). These recessive alleles have been used to breed low-phytate cultivars, inbreds and hybrids, and these have subsequently been used to in biological, agronomic and nutritional studies. One interesting finding is that homozygosity for recessive alleles of barley lpa1 not only reduce seed phytic acid by about 50% but also reduce seed total P by about 15%. The “low seed total P” trait would be useful when grains or grain products are used for biofuels production or in feeds used in dairy or beef production. Future work will continue to study the genetics and biology of seed phytic acid but even greater opportunity exists for progress in the genetics of seed total P. The beauty of forward genetics in this area of research and in other areas of plant biology is its potential as a tool of discovery.